Butylsoyamide protects soybean oil from ruminal biohydrogenation: effects of butylsoyamide on plasma fatty acids and nutrient digestion in sheep

Abstract

Based on previous results showing partial resistance of fatty acyl amides to ruminal biohydrogenation, butylsoyamide was added to sheep diets in an attempt to increase unsaturation of plasma fatty acids. Twelve wethers averaging 34 +/- 3.2 kg BW were randomly assigned to three diets containing either no added fat (control), 5% soybean oil, or 5% butylsoyamide. Dry matter intake was greater (P < .05) for sheep fed butylsoyamide than for sheep fed soybean oil (740 and 581 g/d, respectively), but neither fat supplement differed from the control diet (680 g/d). The soybean oil supplement reduced (P < .05) total VFA concentration (59.0 and 38.7 mM) and acetate:propionate (4.10 and 2.56) in ruminal samples compared with the control diet. Butylsoyamide had no effect (P > .05) on total VFA (54.4 mM) or acetate:propionate (2.96). Total tract ADF digestibility was not affected (P > .05) by either fat supplement. Relative to the control diet, soybean oil increased (P < .05) plasma linoleic acid concentration 22% compared with a 58% increase from feeding butylsoyamide (26.7, 32.6, and 42.1% of total fatty acids, respectively). Linoleic acid concentration in plasma neutral lipids, relative to the control diet, increased 15.8% (P < .05) for soybean oil compared with 64.9% (P < .05) for butylsoyamide (31.6, 36.6, and 52.1% of total fatty acids, respectively). Converting soybean oil triglycerides to fatty acyl amides substantially reduces negative effects of the oil on ruminal fermentation and increases unsaturated fatty acids in plasma. The increase in plasma unsaturated fatty acids demonstrates at least partial resistance of fatty acyl amides to ruminal biohydrogenation and their digestion and absorption postruminally.